Effects of trimonthly progestin administration on the endometrium in elderly postmenopausal women who receive hormone replacement therapy: A pilot study

Objective: The purpose of this study was to determine the effect of trimonthly progestin administration on the endometrium in elderly postmenopausal women who receive hormone replacement therapy. Study Design: This was a prospective, randomized, double-blind, placebo-controlled study at a university teaching program. Twenty-five postmenopausal women who were ≥75 years old with an intact uterus were assigned randomly to receive conjugated equine estrogens (0.625 mg/d plus medroxyprogesterone acetate 5 mg/d for 13 days every 3 months (n = 13) or placebo (n = 12) for 9 months). At the end of the 9 months, patients in the hormone replacement therapy arm continued therapy for an additional 9 months. Statistical analysis was performed with the Student t test, the χ2 test, and the Fisher exact test. Results: Transvaginal sonography was performed at baseline and at 9 and 18 months. Endometrial biopsy was performed if the endometrial thickness was >4 mm or as clinically indicated at 18 months. Patients in the hormone replacement therapy group demonstrated a significant increase in endometrial thickness between baseline (3.9 + 0.8 mm) and 9 months (8.0 + 4.8 mm). There were no cases of endometrial hyperplasia at the 18-month endometrial biopsy. Conclusion: Trimonthly progestin administration in elderly postmenopausal women who receive hormone replacement therapy may be a reasonable alternative to the monthly administration of progestin in hormone replacement therapy. (Am J Obstet Gynecol 2003;189:11-5.)